Sun exposure: An environmental preventer of metabolic dysfunction?

Extreme environments of high ultraviolet radiation (UVR) were avoided by successful implementation of the Montreal Protocol. With increasing temperatures and air pollution levels, the impacts of the climate crisis on sun exposure and human health are uncertain. Emerging preclinical findings suggest that some sun exposure is necessary for optimal metabolic health, with new evidence for beneficial effects of UVR-induced nitric oxide in regulation of important metabolic pathways in the liver and brown adipose tissue. Association studies point toward cardioprotective effects of sun exposure with increases in HDL-cholesterol levels observed in both adults and children. Further work defining likely novel pathways and (neuroendocrine) mediators responsible for these observations and their effects in extreme environments initiated by climate change is needed.